压实膨润土膨胀应变时效性试验及模型研究

本文对高庙子膨润土试样竖向膨胀应变时效性进行了试验和理论研究。首先,3种不同含水率的高庙子膨润土粉末被压实到2种不同干密度,然后保持试样含水率不变分别静置0、1、7、15、30和90天,最后利用膨胀变形仪对静置完成后的试样的水化膨胀变形进行了测量,试验结果表明:试样的水化膨胀曲线呈双曲线型,水化初期膨胀明显,之后逐渐稳定;竖向膨胀应变随初始干密度的增加而增大,与初始含水率关系不明显;最大竖向膨胀应变随静置时间的增长不断衰减,且静置前期衰减明显,后期趋于稳定;基于试验成果,通过类比,建立了压实膨润土的膨胀应变时效性经验模型,拟合结果表明该模型能够较好地反映静置时间对高庙子膨润土膨胀应变的影响。

Test and Model Research of Ageing Effects on Swelling Strain of GMZ01 Bentonite

Ageing effects on the vertical swelling strain of GMZ01 bentonite were investigated by both experiment and theory. Firstly, GMZ01 bentonite powder with three different water contents was compacted to samples with two dry densities. Then, the compacted samples were kept for various periods of ageing time (0, 1, 7, 15, 30 and 90 days) under constant water content conditions. Afterwards, the aged samples were subjected to swelling deformation tests using the swelling deformation apparatus. Test results show that the development of vertical swelling strain of samples with hydration time is hyperbolic. The vertical swelling strain increases fast at the early stage of hydration and then stabilizes gradually with hydration time. Swelling strain increases with initial dry density whereas is almost independent of initial water content. The maximum vertical swelling strain of GMZ01 bentonite decreases with the ageing time. The strain decreases fast at the early days of ageing and then turns to stabilize after 30 days of ageing. Based on test results, an empirical model considering ageing effects is established for the GMZ01 bentonite. Fitting results shows that the established model can reflect well ageing effects on the vertical swelling strain of GMZ01 bentonite.